Re: [Qemu-devel] [PATCH 0/5] tpm: Extend the TPM TIS implementation

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 12/09/2014 09:45 AM, Michael S. Tsirkin wrote:
> On Tue, Dec 09, 2014 at 09:40:28AM -0500, Stefan Berger wrote:
>> On 12/09/2014 09:35 AM, Michael S. Tsirkin wrote:
>>> On Tue, Dec 09, 2014 at 09:18:54AM -0500, Stefan Berger wrote:
>>>> The following series of patches extends the TPM TIS implementation to
>>>> version 1.3. This will lead to a TIS version that supports TPM 2.
>>>> For this I would post relatively small patches afterwards.
>>>>
>>>> Regards,
>>>>     Stefan
>>> Since this is guest visible, should this be limited
>>> to new machine types, to avoid breaking migrating
>>> guests across hypervisor versions?
>> Migration is not currently possible with TPM, since TPM (passthrough) is
>> preventing it.
>>
>>      Stefan
> OK, for live migration, fair enough.
>
> For off-line migration: will the following still work:
> 	- boot guest with tpm 1.3. use tpm in some way
> 	- halt, start guest on old qemu with tpm 1.2
> ?

So this is not a suspend resume operation ? Sure, it will work if the 
driver the OS is using works with a TPM TIS 1.3 interface and also with 
a TPM TIS 1.2 interface.

       Stefan